Belt wrapper for magnetic cores



Oct. 31, 1961 A. s. COOPER BELT WRAPPER FOR MAGNETIC CORES OriginalFiled Sept. 20, 1957 3 Sheets-Sheet 1 FIGI.

Oct. 31, 1961 s. coo 3,006,572

BELT WRA. ER FOR MAGNETIC CORES Oct. 31, 1961 A. s. COOPER BELT WRAPPERFOR MAGNETIC CORES Original Filed Sept. 20, 1957 3 Sheets-Sheet 3 UnitedStates Patent 4 Claims. (Cl. 242-785) This invention relates to themanufacture of magnetic cores and more particularly to apparatus for themanufacture of magnetic cores from magnetic strip material such asgrain-oriented steel strip.

This application is a division of my copending U.S. application, SerialNo. 685,170, filed September 20, 1957, for Manufacture of MagneticCores.

Among the several objects of the invention may be noted the provision ofapparatus for economically manufacturing magnetic cores of the classdescribed which may be quickly and easily assembled with preformedconduc tive windings; the provision of apparatus for manufacturing suchcores which are relatively quiet and have relatively low losses; and theprovision of apparatus for manufacturing cores of the concentric woundoffset but joint type. Other objects and features will be in partapparent and in part pointed out hereinafter.

The invention accordingly comprises the constructions hereinafterdescribed, the scope of the invention being indicated in the followingclaims.

In the accompanying drawings, in which several of various possibleembodiments of the invention are illustrated,

FIG. 1 is a top plan view of a magnetic core-making apparatus of thepresent invention;

FIG. 2 is an elevation of the apparatus of FIG. 1;

FIGS. 3-5 are elevations of three different packets of strip segments asthey appear before being fed into the apparatus of the presentinvention;

FIG. 6 is a top plan view of a portion of the apparatus of FIG. 1 on anenlarged scale illustrating a core-making method of the presentinvention;

FIG. 7 is a side view of a magnetic core made by the apparatus of thepresent invention;

FIG. 8 is a top plan view of a second embodiment of the apparatus of thepresent invention; and

FIG. 9 is an elevation of the apparatus 'of FIG. 8.

Corresponding reference characters indicate corresponding partsthroughout the several views of the drawings.

In making a core in accordance with this invention, a plurality ofstacks or packets of segments of magnetic strip material such as areindicated at 1, 2 and 3 in FIGS. 3, v

4 and are first formed. Each of the stacks or packets consists of aplurality of strip segments with successive strip segments increasing inlength by the factor 21rT where T is the strip thickness. The firststrip segment 1a of stack 1 has a length corresponding to thecircumference of the inside of the core to be formed. The first stripsegment 2a of stack 2 differs in length from the last strip segment 1bof stack 1 by the factor 21rT. Similarly, the first strip segment 3a ofstack 3 difiers in length from the last strip segment 21) of stack 2 bythe factor 21rT. In each packet, the strips are shown as displacedlengthwise so that the ends of the segments are oppositely stepped atopposite ends of the packet.

The packets 1, 2 and -3 are formed into a core by coiling them one afteranother into ring form with each strip segment extending a full turnaround the ring and with the ends of each strip segment forming aflux-transmitting joint, e.g., in butt joint contact, as illustrated inFIG. 7.

This coiling may be carried out by means of apparatus 3,006,572 PatentedOct. 31, 1961 of this invention of the type illustrated in FIGS. 1 and2. As shown therein, the apparatus comprises a support constituted by ahorizontal table or plate 11. Extending upward from this plate on oneside of the plate are shafts 13, 15, 17, 19, 21, 23 and 25 on whichthere are pulleys 27, 29, 31, 33, 35, 37 and 39 for an endless belt 41.The

pulleys and belt are relatively narrow in relation to the strip materialwhich is to be made into cores, and are spaced upward from the plate 11.The pulley 35 is a drive pulley, its shaft 21 being adapted to bepositively driven in counterclockwise direction as viewed in FIG. 1 byany suitable drive means (not shown). The pulleys bound a winding space43 in which is located a cylindrical winding form 45, the axialdimension (width) of which is determined by the width of the stripmaterial. The endless belt 41 leads to the left from drive pulley 35 topulleys 37 and 39, around pulley 27, thence in a loop L around thewinding form 45 to pulleys 29, 31 and 33, and to a belt-tensioningpulley 47, and then around the drive pulley 35. The belt-tensioningpulley 47 is carried by a clevis 49 at the end of a piston rod 51 whichextends from a horizontal air cylinder 53. A lever 55 is pivotedintermediate its ends on a pin 57 extending upwardly from the surface oftable 11. The lever comprises two parallel arms, the left ends of whichlie on opposite sides of the belt and form an arcuate shoe 59 lying inthe throat of the loop L formed by the pulleys 27 and 29, and extendingbetween these pulleys. The other ends of the lever arms are strappedtogether as indicated at 61. Shoe 59 is biased against the surface ofform 45 by an air cylinder 63, a piston rod 65 of which bears againstthe strapped end of lever 55.

In making a core in accordance with this invention utilizing theapparatus shown in FIGS. 1 and 2, the belt 41 is continuously driven bythe drive pulley 35 in the direction indicated by the arrows in FIGS. 1,2 and 6, and the packets 1, 2 and 3 are fed successively one after theother into the gap between pulley 27 and the outer end of shoe 59. Thefirst packet is constrained by belt 41 to coil around form 45 and itsleading end is directed by the shoe so that the ends of the stripsegments come into a flux-transmitting butt-joint contact. When thefirst packet has been thus coiled into ring form, the second packet isfed in, and it coils up into ring form around the first packet with theends of the strip segments in butt-joint contact. When the second packethas been thus coiled into ring form, the third packet is fed in, and

it coils up into ring form around the second packet with the ends of thestrip segments in butt-joint contact. As each packet is fed in, the aircylinder 53 allows for yielding of the tensioning pulley 47 to permitthe necessary expansion of the loop of the belt around the winding formwhile maintaining the belt taut. As the build of the core being formedincreases, the belt 41, core form 45 and tensioning pulley 47 move topositions as indicated by the dashed line of FIG. 1. The core formed bythe three packets of segments is shown in more detail in FIG. 7.

While the coiling of three packets is described above, it will beunderstood that this is only by way of example and ordinarily there willbe more than three packets that will be coiled one after another intoring form.

According to another method of making a core in accordance with thisinvention, a plurality of packets of magnetic strip material such asindicated at 1, 2 and 3 in FIGS. 3-5 are again utilized. However in thisinstance instead of first coiling packet 1 around a core form andthereafter coiling packets 2 and 3 therearound, packet 3 is first coiledinto the form of a ring, with each strip segment extending a full turnaround the ring and with the two ends of each segment in butt jointrelation, as illustrated in FIG. 7. Then, packet 2 is coiled into theform of a ring on the inside of packet 3. Then packet 1 is coiled intothe form of a ring on the inside of packet 2. This type of coiling maybe carried out by means of apparatus of this invention of the typeillustrated in FIGS. 8 and 9. As shown therein, this apparatus comprisesa relatively long and narrow rectangular table 71 At one end of thetable there are vertical side members 105 which support a horizontalcantilever bracket plate 107. This plate 107 is located above the tableand projects out be yond the end 'of the table. Extending down from theplate 107 is a vertical shaft 109 on which is fixed a cylindrical arbor111 which serves as a winding form. At the other end of table 71 is alever 73 pivoted on a pin 75 extending upwardly from table 71. A pulley77 is keyed to a, shaft 79 projecting upwardly from one end of lever 73and rotatable therein. Connected to the other end of lever 73 by apiston rod 81 is a pneumatic cylinder 83, which when actuated controlsthe positioning of shaft 79 in an arcuate slot 85 of table 71. Anendless belt 87 is trained around the pulley 77 and the arbor 11,passing between the side members 105 and under the plate 107.

A pair of guides or idler pulleys 89 and 91 is mounted on shafts 93 and95 which project downwardly from plate 107. These pulleys confine orrestrict the belt 87 immediately adjacent winding form 111, therebyestablishing a throat for the loop L of the belt around form 111. Aforming shoe of arcuate shape, indicated at reference numeral 97, ispositioned between pulleys 89 and 91. A vertical guide plate 99 for thepackets of segments is afiiXed to table 71.

A core form 101 is located below and coaxial with winding form 111. Form101 is constituted by a split metal ring having a width somewhatnarrower than the core to be formed. The inner periphery of form 101corresponds to the outer periphery of the core to be formed and may bevaried by tightening or loosening a bolt 103. Form 101 rests on a table117 carried by a rod 119. This rod is rotatable and axially movable in abase 121.

The forming of a wound core by the apparatus of FIGS. 8 and 9 isaccomplished by feeding in a packet of strip segments, aligned by theguide plate or bar 99, into the throat of the loop L. A packet is formedinto a ring around form 111 by driving belt 87 in a clockwise directionas indicated and tensioning it by actuation of cylinder 83 to movepulley 77. Belt 87 can be driven by powering shaft 79 from aconventional belt and pulley system, or manually. Any tendency for theleading edges of the strip segments in the packet to spring out isovercome by the belt tension and by the shoe 97. After the first packetis coiled around arbor 111 (which has a diameter equal or less than theinner diameter of the core being formed), table 117 is moved toward form111 until the opposing edge of the latter is in contact with the surfaceof table 117. The tension of belt 87 is then released by deactuation ofair cylinder 83 and coiled packet 3 springs open inside the surroundingcore form 101. As the inside diameter of form 101 corresponds to thelength of segment 3b and each of the other segments in packet 3 isshorter by the factor 21rT than the preceding segment, the ends of eachof the segments are 7 This opera brought into substantial butt-jointcontact. tion is'repeated with packet 2 which is thereby positionedinside of packet 3 with segment 2b being adjacent 'seg ment 3a. Thus awound core as shown in FIG. 7 is formed.

It is preferred that the butt joint of the outer segment of'each packetbe angularly displaced from the butt joint of the inner segment of thepacket surrounding it. This displacement is preferably of such magnitudethat the spacing between such adjacent segment butt joints will be equalto'21rNTWhere N equals number of segments from the inner circumferenceof the Core. That is, the butt joints of segments 3b, 2b and 1b are eachaligned on a radius of the core formed. In some instances, however, itis desirable that these butt joints are not radially aligned, but arepositioned on difierent radii of the core.

The cores thus formed are then banded by a steel strap or tack weldedacross the butt joint of segment 3b to permit them to be removed fromthe core form 45 or 101. If the conventional rectangular core isdesired, the cores formed by this invention can be so formed byhydraulic jacks or presses, after which these rectangular cores are thenannealed to remove the resulting mechanical stresses. The annealed coresare then dissembled packet by-packet, and assembled in the same relativepositions around preformed transformer windings, packet 1 being removedand reassembled around the windings first, followed by packets 2 and 3.

It is to be understood that the core forms used in the apparatus of thepresent invention are not limited to a circular shape, but may be ofelliptical or other configurations.

In view of the above, it will be seen that the several objects of theinvention are achieved and other advantageous results attained.

As various changes could be made in the above constructions withoutdeparting from the scope of the invention, it is intended that allmatter contained in the above description or shown in the accompanyingdrawings shall be interpreted as illustrative and not in a limitingsense.

I claim:

1. Apparatus for making magnetic cores from packets.

of segments of magnetic strip material comprising a table, a windingform supported on the table and extending upward therefrom, said windingform being rotatable ona vertical axis and being shiftable laterally onthe table, a plurality of pulleys extending upward fiom the table, anendless belt trained around the pulleys and the winding form, one ofsaid pulleys being a drive pulley, said belt extending from a first ofsaid pulleys in a loop around the winding form and thence around asecond of said pulleys, said first and second pulleys being spaced aparta distance such as to define a throat. therebetween narrower than thediameter of the winding form for insertion therethrough of packets to bewound on said winding form, a shoe movably mounted in said throat, andmeans for biasing said shoe into engagement with the winding form andpackets being wound thereon.

2. Apparatus for making magnetic cores from packets of segments ofmagnetic strip material comprising a table, a winding form supported onthe table and extending upward therefrom, said winding form beingrotatable on a vertical axis and being shiftable laterally on the table,a plurality of pulleys extending upward from the table, an endless belttrained around the pulleys and the winding form, the width of the beltbeing less than the height of the winding form, one of said pulleysbeing a drive pulley, said pulleys bounding a winding space in which thewinding form is located, said belt leading inward to said winding spacearound a first of said pulleys, thence in a loop around the winding formand thence outward and around a second of said pulleys, said first andsecond pulleys being spaced apart a distance such as to define a throattherebetween narrower than the, diameter of the winding form forinsertion therethrough of packets to bewoundv on said winding form,aglever pivoted for swinging movement on top of the table on. a verticalaxis. lying within the confines of the endless belt, said lever havingspaced upper and lower portions straddling the belt and extending acrosssaid throat from one side of the throat toward the other and terminatingshort of the other side of the throat to provide a space for insertionof packets to be wound on said winding form, and meansfor biasing saidlever to swing in the direction for engagement of said portions of thelever with the winding form and with packets being wound on said windingform.

3. Apparatus for making magnetic cores as set forth in claim 2 whereinone of said-pulleys is a belttensioning idler pulley movable laterallyover the table, and wherein means is provided for biasing said idlerpulley to tension said belt to hold it taut around the winding form andpackets wound thereon and which permits said loop to expand around thewinding form as packets are wound thereon.

4. Apparatus for making magnetic cores as set forth in claim 3 whereinsaid upper and lower portions of said lever are formed to provide anarcuate shoe engageable with said winding form and with packets beingWound on said winding form.

References Cited in the file of this patent UNITED STATES PATENTS

